ARUM RUPICOLA

PROTOLOGUE: Arum rupicola , published in Diagnoses Plantarum Orientalium Novarum 13: 7 (1854). The protologue is reproduced below.

SYNONYMS:

HOMOTYPIC SYNONYMS: Arum hygrophilum var. rupicola (Boiss.) Boiss.

DISTRIBUTION: E. Aegean Is. (Lesvos) to Iran and Israel: Armenia, Azerbaijan, Cyprus, East Aegean Is., Georgia-GE, Iran, Iraq, Israel, Jordan, Lebanon, Palestinian Territories, Syria, Türkiye.

DISTRIBUTION NOTE: iNaturalist: Aksaray, Nicosia, Niğde.

SPECIES DESCRIPTION:

Tuberous herb sprouting in early winter from a discoid, vertically orientated tuber 4–8 cm across, 2–3.5 cm thick. Petiole terete, 10–55 cm long, 3–6 mm wide, pale to mid-green. Leaf-blade oblong-sagittate to oblong-hastate, apex subacute to obtuse, occasionally rounded, 8–25 cm long, 4–18.5 cm wide, mid-green.

INFLORESCENCE:

Inflorescence odourless. Peduncle exceeding the leaves, terete, 10–65 cm long, 4–12 mm wide, pale to mid-green. Spathe 11.5–40 cm long; spathe-tube oblong cylindric, 2–7 cm long, 0.75–2.5 cm wide, moderately to strongly constricted apically, exterior pale to mid-green, very rarely mid-brown, sometimes with purple staining along the margin at the top, interior white; spathe-limb linear-lanceolate to lanceolate, 9.5–33 cm long, 2–8 cm wide, erect at first but soon flopping either backwards or forwards and curling apically, margins sometimes crispate, acute to acuminate, externally pale to mid-green, often heavily stained with purple along the margin, sometimes ± entirely purple, rarely entirely green, very rarely mid-brown, internally pale greenish white ± stained with deep purple or maroon, more rarely greenish white with a very narrow purple margin, very rarely mid-brown. Spadix subequal to or exceeding the spathe-limb, 8–33 cm in total length; appendix cylindric to conic-cylindric, sometimes massively so, short-stipitate to almost stalkless, 6–32 cm long, 13–25 mm wide, deep to mid-purple to grey-lilac, rarely brown, dirty orange or yellow, often darkening rapidly on the opening of the inflorescence. Staminodes in 2 to 4 whorls forming a zone 2–10 mm long; bristles filiform, flexuous, 1.5–9 mm long, violet to deep purple; bases compressed conic, smooth, off-white. Interstices: upper and lower 0–2.5 mm long, usually with numerous rudimentary sterile flower bases, off-white. Staminate flowers in an oblong zone 3–25 mm long, 5–10 mm wide; anthers and connectives deep violet. Pistillodes in 2 or 3 or rarely 4 whorls; bristles filiform, flexuous, 1.5–9 mm long, violet to deep purple; bases compressed conic, smooth, off-white. Pistillate flowers in an oblong cluster 7–25 mm long, 5–17 mm wide; ovaries oblong-ovoid, 2–2.5 mm long, somewhat truncate apically, pale to mid-green, often stained with purple apically (this feature differing even within the same population); stigma purplish grey. Fruiting spike oblong-cylindric, 3–6 cm long, 1.5–2.5 cm wide when mature; berries ovoid, 5–11 mm long, 2–5 mm wide.

ECOLOGY:

Rocky hillsides, amongst Quercus scrub, margins of Cedrus forest, open montane pasture; altitude: 600-1700 m

DISTRIBUTION MAPS:

ETYMOLOGY:

Latin rupes, “rock”, with-cola, “dweller”: a plant of rocky hillsides.

NOTES:

1. The spadix is strongly thermogenic, reaching about 40 °C and running 15 to 20 °C above ambient from about 17:00 to 23:00.¹²

2. Long described as scentless, the variety rupicola is not: its appendix releases numerous sesquiterpenoids together with traces of p-cresol and assorted alcohols, esters and ketones.¹³

3. With Arum jacquemontii and Arum korolkowii it forms subsection Tenuifila, the three standing together in molecular phylogenies.⁹

REFERENCES:

1. Plants of the World Online, Royal Botanic Gardens, Kew — Arum rupicola

2. Diagnoses Plantarum Orientalium Novarum 13: 7 (1854) — protologue.

3. iNaturalist: Arum rupicola

4. Boyce, P.C. 1993. The Genus Arum: a Kew Magazine Monograph. Royal Botanic Gardens, Kew.

5. Boyce, P.C. 2006. Arum – a decade of change. Aroideana 29: 132–137.

6. Diaz et al. 2006. The effectiveness of some mechanisms of reproductive isolation in Arum maculatum and A. italicum (Araceae). Botanical Journal of the Linnean Society.

7. Chartier et al. 2013. Geographical variations of odour and pollinators, and test for local adaptation by reciprocal transplant of two European Arum species. Functional Ecology.

8. Albre et al. 2003. Pollination ecology of Arum italicum (Araceae). Botanical Journal of the Linnean Society.

9. Linz et al. 2010. Molecular phylogeny of the genus Arum (Araceae) inferred from multi–locus sequence data and AFLPs. TAXON.

10. Gibernau et al. 2025. Mediterranean island endemic Arum pictum emits isomyocorene as a major component of floral scent. Comptes Rendus. Chimie.

11. Gibernau et al 2003. Arum Pollen longevity & viability.

12. Gibernau, Macquart & Przetak 2004. Pollination in the genus Arum - a review. Aroideana 27: 148.

13. Kite et al. 1998. Inflorescence odours and pollinators of Arum and Amorphophallus (Araceae). In: Owens & Rudall (eds), Reproductive Biology, pp. 295-315. Royal Botanic Gardens, Kew.

Additional photos by David Scherberich